In recent years, according to an increase in density and improvement of functions of electronic circuit substrate, a component incorporated substrate having structure in which electronic components are embedded in an insulating substrate which is an insulating layer has been attracting attention (see, for example, Patent Document 1). In such a component incorporated substrate, a wiring pattern is formed on the surface of the insulating substrate. The component incorporated substrate can be used as a module with other various electronic components surface-mounted in predetermined positions of the wiring pattern. The component incorporated substrate can also be used as a core substrate in manufacturing a component incorporated multilayer circuit substrate with a build-up method.
In such a component incorporated substrate, it is necessary to provide a connecting section that electrically connects the wiring pattern on the surface of the insulating substrate and a terminal of an electronic component in the insulating substrate. As a conventional manufacturing method for a component incorporated substrate, first, a copper layer, which should be a wiring pattern, is formed on a supporting plate. A connecting section is formed in a predetermined position on the copper layer by solder paste. The electronic component is disposed such that the terminal is positioned on the connecting section. Subsequently, the connecting section and the electronic component are embedded by an insulating material, which becomes the insulating substrate. An intermediate product incorporating the electronic component is obtained. Thereafter, the supporting plate is peeled off the intermediate product. The exposed copper layer is formed into a wiring pattern having a predetermined shape, whereby a component incorporated substrate is obtained.
Incidentally, when the other various electronic components are surface-mounted on the surface of the component incorporated substrate, reflow soldering is performed. Therefore, the component incorporated substrate is exposed to high temperature equal to or higher than a melting temperature of solder every time the reflow soldering is performed. Therefore, it is likely that reliability of the connecting section between the wiring pattern and the terminal section of the electronic component is deteriorated.
Therefore, in the component incorporated substrate, in order to attain improvement of thermal reliability of the connecting section between the wiring pattern and the terminal section of the electronic component, it is conceivable to use, as a material forming such a connecting section, copper that has a high melting point compared with the solder and is less easily affected by heat in the reflow soldering. The connecting section formed using the copper is formed by, for example, after embedding the electronic component in the insulating substrate, providing a connection hole that extends from the wiring pattern on the substrate surface to the terminal of the electronic component in the substrate and filling the copper in the connection hole using a plating method. In this case, since the connection hole has to be accurately formed toward the terminal of the electronic component in the insulating substrate, in a manufacturing process, it is necessary to improve accuracy of positioning of the electronic component and accuracy of specifying of a terminal position. A form of a manufacturing method for a component incorporated substrate that attains improvement of these kinds of accuracy is explained below.
First, a supporting plate is prepared and a copper layer is formed on the supporting plate. A mark consisting of a columnar body of copper is formed on the copper layer by the plating method. Subsequently, an electronic component is positioned in a predetermined position on the copper layer with reference to the mark and fixed by an insulative adhesive. Thereafter, the fixed electronic component and the mark are covered with an insulating material to form an insulating layer as an insulating substrate embedded with the electronic component. Thereafter, the supporting plate is peeled to expose the copper layer. In the exposed copper layer, a portion where the mark is present is etched and removed, whereby the mark is exposed. A terminal position of the electronic component is specified with reference to the exposed mark. A connection hole reaching the terminal is formed. Thereafter, copper plating is applied to the entire copper layer including the connection hole to fill the connection hole with the copper, whereby the copper layer and the terminal are electrically connected. Finally, the copper layer on the surface of the insulating substrate is processed into a predetermined wiring pattern, whereby a component incorporated substrate is manufactured.
With the manufacturing method, since the same mark is used as a reference for the positioning of the electronic component and the specifying of the terminal position, it is possible to accurately perform the positioning of the electronic component and the specifying of the position of the terminal.